Machine for ramming up molds and the like



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May 28, 1946. s. M. sTooDY ETAL y MACHINE FOR RAMMING UP MOLDS AND THE LIKE 6 Sheets-Sheet 2 Filed July 20, 1942 ,S7/n En?. iraoo .R4/.PHL A505,

` INVENToR ATTRNEYS May 28, 1946.

MCHINE FOR RAMMING UP MOLDS AND THE LIKE Filed July 2o, 1942 6 sheets-sheet s O 7 i e o 97 o 'o .56 sa 85 a 54 as O O L 93 M 105 A i i ,/6) I 104 I' 51 v101 l [i f7..

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May 2s, 1946.`

s. M. sTooDY `ETAL 2,401,198 MACHNE FOR RAMMING UP MOLDS AND THE LIKE Filed July 2o, 1942- e sheetsfsneet 4 o o ff l 104 a 95 9 v- C 101 Y i; fi., 17 2f /f Y 1021,05

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ATTORNEYS May 28, 1946.

s. M. sTooDY ET Al.

MACHINE FOR RAMMING UP MOLDS AND vTHE LIYKE 6 Sheets-Sheet Filed July 20, 1942 'iff-i INVENTORS ATTORNEYS May 28, 1946.v n s. M. sTOoDY E'r'Al.v Y 2,401,198

MACHINEAFOR RAMMING UP MOLDS AND THE L'IKE Filed July 20, 1942 6 sheets-sheet vfs 54 i' l] I f7 g s E Wf/ Num \\\\\\\\\\\\\\\\S ATTORNEYS.

Patented May 28, 1946 RAMlWIN THE MACHINE FOR T' OFFICE- GUPMoLDsAND` LIKE i Shelley M. stoody and Ralph L. Abos; Whittier,

Calif., assignors to Stoody Company, Whittier,

Calif., a corporation of California Application July 20, 1942, Serial No.451,540 (cl. `afa-46) 3 Claims.

This invention relates to a method and means for ramming up molds and the like which molds are useful for casting purposes.

There are numerous instanceswhere a multiplicity of molds mustbe rammed up about identical patterns to Venable casting of a multiplicity of identical articles. The present invention contemplates a method and a machine which will enable such molds to be easily, quickly, and uniformly rammed up.

In ramming up molds it is highly desirable fand usually quite important that the molding sand or molding composition be rammed up or packed in a ilask about a pattern with a high degree of uniformity for if the molding material is loosely rammed in one portion of the mold and tightly packed or compacted in another portion of the mold the castings obtained are apt to be nonuniform and faulty. This is particularly true where the casting is formed of a relatively high melting point metal alloy and where precision castings are required.

A primary object of the present invention is to therefore provide a means and apparatus for ramming up molding material in a ilask about `a `pattern in such a manner that a high degree of uniformity can be obtained. l

In general, the present method and apparatus Vcontemplate introducing molding material into a flask in a succession of small quantities, applying pressure to each quantity after it has been introduced, and while the pressure is being applied, imparting a plurality or series of sh'arp blows or impacts to the material. We have found that if the molding materialis introduced into the flask about the pattern `and straight or simple pressure is appliedthereto without impact that the molding material tends to stratify under -the pressure so that there are striations or seams through' it. These usually are most noticeable under the area or areas of application of `pressure. The portions of the mold that are not directly beneath the area or areas of application of pressure are apt to remain loose. However, if pressure is applied to the molding material fed into the flask and a plurality of impacts or percussive blows are applied by the pressure-applying means to the moldingmaterial while the pressure is being applied, we` find that the formation of striations or seams in themolding material is largely, if not, entirely, eliminated. Furthermore, the impacts tend to distribute the compression created by the pressure applied throughout the molding material so that it is uniformly compacted not only beneath the area vary considerably.

orlareas thatapply the pressure but elsewhere throughout the mold. Consequently, if the pressure-applying means does not accuratelyiit the interior ofthe flask or-` closely t about the pattern, the molding material is nevertheless firmly compacted throughout the interior of the flask and closely around the surfaces of the pattern.

Another object of the invention is to provide a machine for ramming up moldingmaterials around .patterns in flasks wherein molding Amaterial `is successivelyl fed in small quantities into the flask and rammed up in the above-described manner before the introduction of a succeedingquantity of molding material is introduced andto provide a pressure-operated means for moving aramming hammer into and out of the liask. Inthis manner` as the flask is gradually lled by the addition of consecutively introduced amounts of molding material the pressure with'. which the ramming hammer is forced against themolding material is maintained uniformregardless of the height of the molding material'in the flask. In` other words, the pressure applied by the ramming hammer will remain the same when the"V flask is substantially .iilled as Whenthe filling of the flask has'jllst started.

, VA further object oftheinvention is to provide a conveniently arrangednmeans for varying the length of timethat the 'ramming hammer applies pressure to the, molding material in the flask and .consequently the number of percussive blows imparted thereby during each cycle of operation of the machine. Thus some molding materials possess such characteristics that they need only be lightly rammed up in the flask to secure the desired castings. Other molding materials have such characteristics th'at they must be heavily vrammed up in the iiasl:L and rendered quite compact and dense. By means` of the adjustment which the present uinvention affords, the machine can be quickly adjusted to take care ofthelrequirements of the molding materials whichmay `Still another object of the invention is to provide a molding machine having a novel, simple, and highly advantageous means for mounting a flask thereon, and also a means for holding` a pattern therein in desired position.

With the foregoing and other objects in View, which will be made manifest inthe following detailed description and specifically. pointed out in the appended claims, reference is had to the ac:` companying drawings for an illustrative embodiment of the invention, wherein: l, `Figure 1` isa front" View in elevationof the Fig. 3 is a view in side elevation of the mold-y ing machine illustrated in Fig. 1;

Fig. 4 is a view in vertical Section illustrating the upper portion of the pneumatic hammer that forms a part of the presentinachine and illustrating the control mechanism of the machine;

Fig. 5 is an enlarged view in front elevation of the upper portion of the machine illustrating it in that position wherein the ramming. hammer is being withdrawn from the flask;

Fig. 6 is a View similar to Fig.' 5 illustrating the machine in that position wherein the ramming hammer is being forced downwardly into the ask:

Fig. '1 is a sectional view. taken substantially upon the line 1-,-'I upon Fig. 5 in the direction indicated;

Fig. 8 is a horizontal section taken substantially upon the line 8-f8 upon Fig. '1 in the direction indicated;

Fig. 9 is a vertical section taken substantially upon the line 9-:9 upon Fig. l in the direction indicated; and

Fig. l0. is a. horizontal section taken substan tially upon the. line lof-,I upon Fig. 9.

Referring to the accompanying drawings wherein similar reference characters designate similar parts throughout, the machine comprises a frame supported on. a suitable base IIland preferably consisting. of a pair of upright columns II and I2 braced. by suitable bracing indicated at I3. The columns II and I2 support upper and lower'body plates I4 and I5 on which therel are bearings orguides I for vertically reciprocable rails 'or slide bars I'I and I8 that are spaced forwardly of-theA columns IIl and` I2.

The flask that it is desired to ram` up with molding composition or` molding sanduis indicated at I9, and whilethis'flask. may assume different sizes and shapes. depending upon the nature of the casting that it is desired to produce the flask illustrated is inthe form of a short, hollow, carbon cylinder open at both top and bottom.

The pattern of the casting that is to be produced is illustrated at 23. This pattern will likewise assume various sizes and shapes.V depending upon the nature of the casting that is to be produced. If possible, however, it is highly desirable that the pattern be equipped at its upper end with one or more extensions 2I receivable in grooves 22 formed in the interior walls ofthe flask I3 so as to support and maintain the body of thepattern centrally of or in proper position with relation to the flask. Wefind it desirable also to have the bottom ofthe pattern equipped with an extension 23 that normally will project downwardly below the bottom of the flask. This extension is to be engaged by a holding means when the flask and pattern are positionedon the machine sothat the bottom ofthe pattern will likewise be held either centrally ofr andA in proper position within the flask.

' On the lower body plate or frame plate I5V there is a flask supportpreferably consisting of 25` may have its upper surface recessed to form through a supply pipe 3B. A spring 3| a seat for the bottom of the flask I9, see Fig. 2. The lower plate is preferably apertured to receive the extension 23. The upper plate has secured to its underside adjacent the forward end thereof a small plate 25 that constitutes a stationary jaw engageable at its rear end with the forward side of extension 23. The movable jaw is indicated at 21 and is slidably mounted in the underside of plate 25. This jaw is adapted to be forced forwardly by a pneumatically operated diaphragm 28 housed within a housing 29 and supplied with compressed air or the equivalent enclosed within the housing urges the diaphragm into jawretracting position. whenever pressure in supply pipe 3,0 is released. When pressure is applied to the diaphragm 28 through supply pipe 3D the movable jaw 2'Iv is forced forwardly, see Fig. l0, and, cooperates with the stationary jaw 26 to clamp on extension 23, thus firmly holding the bottom of the pattern in proper position with relation tothe flaskV I8. O n release of the. pressure, spring 3l retracts, the movablejaw 21 so asV to. disengage the extension 2.3 and enable the flask and the contained pattern to. be removed.

The supply pipe 3 0 is supplied with compressed air or the equivalent from any suitable source and is controlled by a three-wayvalye 3,2, see Fig. l, preferably located at anyl convenientlocation near the front of the machine. This threeway valve on manipulation will connect the interior of housing 2S! with either the source of compressedair toA close the movable jaw 21 or to the atmosphere to allow the movable jaw: 2:1 to be opened under-the action of spring 3.1.

As a means. for clamping the flask t9; on its support afforded bythe plates. 24 and 25 a crosshead 3.3 is provided preferably recessed on its underside to receive thetop of the ask, see Fig. 9. This crosshead. is adapted to be pulled downwardly by a pair of pull rodsl 3.4. which are slidably mounted in guides 35, see Fig. 9, mounted on the back off a cross bar 36. that connects the lower bearings or slides I- for the rails I1 and I8'. Springs. 31 surround. the pull. rods above the cross bar 3.5. andv are adapted to bev compressed when the crosshead 33Y is pulled. downwardly. They urge the crosshead into vuppermost or flask releasing position whenever the lower ends of the pull rods are free tobe moved. upwardly. thereby. The lower endsv ofthe pullv rodsA 3.4; areconnected to a crosshead 33 which, in turn, is connected by a link 39 toa crank 40. on arockshaft Y two superposed plates 24jand125. The upper plate Y '4I suitably mounted on bearings` secured to the lower frameiplate I5. The rockshaft talV is operable by a hand lever 2f so thatv when thehand lever 42 is forced downwardly crosshead 38 will pull crosshead 33.' downwardly into clamping engagement with the flask compressing the compression springs 31. As a means for locking the crosshead 38A andconsequently the crosshead 33 in flask clamping position and also tightening the crosshead 33- against thetop of the flask with considerable mechanicaladvantage the crosshead 33 is equipped with a detent 43 engageable with a shoulder for-ming one side of a notch 44 in the rearside of a hold-down bar 25 which is pivotally suspended from between ears 46 on the underside of the plate 24. A rockshaft 61 extends through the ears,` and is operable by a handle 48. This rockshaft however has an eccentric portion 49 that extends through'the upper end ofp'a holdfdown bar 45. ,The arrangement is such thatthehold-down bar willnormally swingby grav-ity in a rearward Aciprocation of its hammer 51.

direction against the detent 43. Consequently, when lever 42 is pressed downwardly theV detent 43 engages the rear edge of the hold-down bar and ultimately enters the notch 44. The handle 48 can then be swung into the position shown in Fig. 9 which, because of the eccentric portion 49 on the rockshaft 41 forces the hold-down bar 45 downwardly a short additional distance with great mechanical advantage, thus causingthe crosshead 33 to clamp upon the top of the flask with considerable pressure. The hold-down bar 45 serves to hold the crosshead 33 in this clamping position even though lever 42 is released.

When it is desired to release the flask I9 the handle 48 is swung upwardly and forwardly `or in a clockwise direction from the phantom line position shown in Fig. 9 which causes the eccentric on the rockshaft 41 to release the high tension on the tension rods 34. The rockshaft also carries a small arm 58 having a lateral extension that extends behind the hold-down bar 45 so that when the handle 48 nearly completes its upward and forward swinging movement this extension engages the back of the hold-down bar and disengages it from the detent 43. The compressed springs 31 then become effective to lift the crossheads 33 and 38 and the tension rods 34 into their uppermost positions clearing the top of the flask |9 to enable its being removed. Three crossheads 52, and 53 connect the rails or slides I1 and I8 so as to be vertically reciprocable therewith. The upper crosshead 5| provides a mountl for a pneumatic hammer which may be of any preferred or conventional construction. This hammer, generally desig- `nated at 54, is supplied with compressed air through a flexible tubeor hose 55. It is provided with a control or trigger 58 that delivers the compressed air to the operating mechanism of the hammer which produces a short vertical re- The second crosshead 52 serves to support a hopper 58 into which the molding material or molding sand 59 is placed. It also provides a brace portion 68 that clamps about the lower portion of the pneumatic hammer to hold it in position. The lower crosshead 53 provides a suitable bearing within which is vertically reciprocable a hollow ramming hammer 6|. This ramming hammer is slidably mounted in the crosshead 53 and has vertical grooves or keyways 62 formed therein into which partially project balls 63 to form an anti-friction splined connection between the ramming hammer 6| and the crosshead whereby the ramming hammer maybe vertically reciprocated but will be held against rotation relatively thereto. The ramming hammer 6| is separate from the hammer 51 of the pneumatic hammer 54. It is connected thereto however by a rubber shield E4 preferably in the form of an accordion pleat at cross-section which enables relative movement to take place between the hammer 51 and the ramming hammer 6 I if occasion requires, but `prevents the molding material 59 from entering between the hammers. As indicated on Fig. 9 the ramming hammer is hollow except at its upper end where it isV engageable by the hammer 51. It is equipped with one or more ports 65 adjacent its upper end through which the molding material 59 may pass. A cup 66 is threadedly mounted or is otherwise rigidly secured on the ramming hammer 6I and telescopes over the spout at the lower end of the hopper. A compression spring 61 is `compressed between the crosshead 53' and. the

cup 66 and serves to continually urge theram-A ming hammer into its uppermost position.` 1

As indicated on Fig. 9, sides of the bottom of tlie ramming hammer are recessed as at 68 to accommodate the extensions 2| at the top of the pattern when the ramming hammer isin its lowermost position within the flask I9. 'Ihe ramming hammer thus provides areas 69 at its lower end adapted to engage and impact with the molding material 59 that is fed from the hopper 58 through ports 65 downwardly through the hollow ramming hammer.

The weight of the rails or slides I1 and I8, the crossheads thereon, the hopper 58 and its contents, and the pneumatic hammer, is largely counterbalanced by counterbalance levers 10 pivotally mounted on each side of the frame. The forward ends of these levers are connected by links 1| to the upper crosshead 5|. Counterweights 12 are adjustably mounted on the rear ends of the levers.

The means employed for vertically reciprocating the carriage that comprises the rails I1 and I8, the crossheads 5|, 52, and 53 and the structure mounted thereon is a pneumatic ram comprising a cylinder 13 mounted on the upper frame plate I4. Within this cylinder there is a double-acting piston 14 the rod of which, 15, extends through a stuiling box 16 and is connected as at 11 to the upper crosshead 5|. When compressed air is delivered to the ,cylinderA 13 on top of the piston 14 the piston is forced downwardly thus forcing the carriage downwardly and introducing the lower end of the ramming hammer into the flask. Conversely, when compressed air is delivered to the cylinder 13 below piston 14 the piston 14 and the carriage are elevated. On the forward side of the cylinder there is mounted a holder 18 on which is mounted a slide 19 for a vertically reciprocable cam 88. This cam is held onto the slide by means of cap screws or the equivalent indicated at 8| which extend through slots 82 therein. The side edges of this cam are engageable with the heads 83 of valve stems 84 of valves 85, 88, 81, and 88. Compressed air is supplied to the valves 85 and 88 through a supply pipe or conduit 89. i

In the position shown in Fig. 5, the carriage is being elevated as indicated by the arrow at the bottom of this gure. The line of ow of compressed air is from the supply pipe 89 through valve 88 which has been opened by the cam 88 through a control or throttle valve 99 and through tubing 9| to the bottom of the cylinder 13. Air in the top of the cylinder is allowed to exhaust therefrom through tubing 92 through valve 86 which has also been opened by the cam to the outlet 93 where it may discharge into the atmosphere. that valves and 81 controlling flow to and from the top and bottom of the cylinder 13, respectively, are allowed to close by the cam 89.

` In the position shown in Fig. 6, the carriage is descending as indicated bythe arrow at the bottom of this gure. In this position the line of ow from supply pipe S9 is through the valve 85 past a throttle or control valve 94 and thence lihIOllgh tubing 95 to the top of the cylinder 13. The compressed air, however, has a divided path. Part of the air entering tubing 95 and passing to the top of the cylinder and the balance owing past athrottle or control valve 96vthrough tubingi91 to a timing cylinder 98, the exhaust from which is controlled by a control valve 99 In this position it will be noted.

before passing into the atmosphere. In this position it will be noted that the cam 80 has opened valve 8'! permitting air in the bottom of cylinder 13 to be exhausted through tubing HNI to the exhaust outlet 93. It will also be noted that in this position valves 86 and 88 have been allowed to close kby the valve member. A

A lever ltl is pivoted as at |92 to the holder 18 and has a pin and slot connection |03' with the cam 80. A tension spring connects the swinging end of this lever with an adjustable support |05. This spring andV support are soarranged that the spring functions as. a snap-over spring. Thus, if the cam 89 is moved into the position shown in Fig. 5, tension of the spring IM is such as to cause the lever to tend to retain the cam member in this position until forcibly moved therefrom. Conversely, if the cam member has been moved into the position shown in Fig. 6, the tension of the spring |94 will tend to retain the cam B in this position until forcibly moved therefrom. The cam can be shifted into the position shown in Fig. 6 by means of a push rod |06 that is mounted for vertical reciprocation relative to the upper crosshead 5| by means of a bracket |01. This push rod whichris vertically slidable in the bracket can be elevated relatively to the crosshead 5| by means of a lever |08 that is pivoted on the bracket as at |09 `and which is connected to the push rod by means of a link |0.- The lever has a handle by which it may be swung into the dotted line position shown in Fig. 4, or into the full position shown therein. The lever has a nose |12 thereon which is engageable with the trigger 55 of the pneumatic hammer when the lever is swung into the dotted line position as indicated in Fig. 4. In this position it will Vbe noted that a heel H3 engages the crosshead 5| in such a position that the pivotal connection H4 between the link H0 and the lever |98 is slightly beyond the center line join-Y ing the pivotal connection H5. Consequently, when the lever, is shifted into the dotted line position shown in Fig. 4, the trigger of the pneumatic hammer will be retained in depressed `position` and the push rod N6 will be elevated into its'uppermostposition wherein it is engageable withthe bottom of the cam 89. Consequently, when the carriage rises to the top of its stroke the push rod W5 will engage the cam 89 and shift it. from the position shown in Fig.- 5 to the position shown in Fig. d, reversing the positions of the valves from the `positions shown in Fig, 5 to the positions shown in Fig. 6 and causing air to be admitted to the top of the cylinder 13 to force piston. 'M downwardly therein.

The means for shifting the cam 89 from the position shown in Fig. 6 into the position shown in Fig.Y 5 consists of the piston that is operable within the regulating cylinder 98. This piston, indicated at| 6, see Fig. 7, has a rodfl |T extending down through the bottom of the cylinder so as to be engageable with. the top of the cam 8D. It is urgedV into uppermost position by lmeansv of a spring H3. Air beneath the piston and-within -the cylinder may escape therefrom through a bleeding'port H9 which is of predetermined size.

When the machine is in the position shown in Fig. 6, a portion, of the air delivered through valve 35 passes to the top of the cylinder '13, as previously explained, and the balance thereof passes through tubing 9i into the top of the control cylinder 93., The rate at which this' air may build up a pressure on top of piston l I6 depends upon the extent to which control valve 99 is Cil opened. Thus, if valve 99 is opened rather Widely most of the air delivered through tubing 91 may escape therepast withV the result that considerable time is required to build up an air pressure on top of piston I6 to depress it against the action .of spring H8. Conversely, if valve 99 is nearly closed the pressure within the cylinder 98 on top of piston H6 will build up quite rapidly with the result that the piston will be depressed against the action of spring ||8 in a relatively short time. Whenever the piston is depressed the lower end oi its rod ||1 engages the top of cam 80 and shifts it from the position shown in Fig. 6 into the position shown in Fig. 5. Whenever the cam t0 is shifted from the position shown in Fig. 6 into the position shown in Fig. 5, the carriage, pneumatic hammer, ramming hammer, and associated structure are lifted from within the iiask. Thus, by opening or closing valve 99 the length of time that the lower end of the ramming hammer remains in the flask can be varied. If valve 99 is nearly closed the ramming hammer will remain in the ask only a short period of time before sufliicent pressure builds up in cylinder 98 to actuate piston H8 and eiect a shift of cam 80. On the other hand, if valve 99V is opened rather widely, considerable time `must elapse before the required pressure can build up to cause piston |56 to shift cam 80 and bring about a Withdrawal of the ramming hammer from the flask. Thus, the length of time that the ramming hammer remains in the flask can be varied.

The operation of the above-described machine is as follows.: Assuming that the flask i9 with its pattern 2i) disposed therein is positioned on the flask sup-port aiforded by the plate 25 and has been clamped in position thereon by operation of the lever 42 and the handle B, the machine is started in operation by swinging handle lilv from the full line position shown in Fig. 4 to the dotted-line position. This projects push rod l upwardly and as the carriage is initially at the top of its stroke, the upward movement ofthe push rod shifts thecam 80 into the position shown in'Fig. 6. At the same time the triggerl of the pneumatic hammer is depressed so `that the pneumatic hammer has its Y hammer continuously striking and reciprocating the ramming hammer 6|. The movement of the ramming hammer 6| brin-gs about a simultaneous short reciprocation or Vibration of the cup 59 which tends to feed the molding material 59 through the port S5 down through the ramming hammer 5| and into the ask while the carriage and structure mounted thereon is descending. The molding material 59 is thus fed into the bottom of the iiask about the pattern while the carriage is descending. When the lower end of the ramming hammer 6| encounters this material it issubjectedto the pressure exerted by the pressure of the compressed air admitted to the top of cylinder 13 on top of piston 14; This pressure is maintained while usually two or more percussive blows are transmitted to the ramming Vhammer 6| by they pneumatic hammer. In the course of a relatively short time depending upon thevextent to which valve 99 is opened the carriage is elevated, and during this upward move'- ment the pneumatic hammer continues to operate transmitting downward blows to the ramming Ahammer 6|. These blows however' are mere idle blows inasmuch as the ramming hammer is ascending; WhenA the carriagereaches the top of its. stroke pushrod |06 engages cam 89, shifts the direction of flow of compressed air into the cylinder 'i3 and bringing about a descent of the carriage thus completing one compl-ete cycle of operation. Each cycle of operation will, of course, cause a small additional quantity of molding material to be rammed up in the bottom of the flask about the pattern. However, regardless of the elevation to which the mold material has risen Within the flask it will be noted that the pressure exerted thereon by the ramming hammer 6l independently of the percus-sive blows is constant, this being purely dependent upon the pressure oi the compressed air applied to the top of piste-n 'ii which is assumed to be obtained from a source of compressed air under constant pressure. The magnitude of the percussive blows transmitted to the ramn'iing hammer iii likewise is constant. Operation of the machine is continued until the flask has been completely rammed up after which the machine can be turned by swinging handle Ell into the full-line position shown in Fig. 4. rlhis releases trigger 56 shutting on the pneumatic hammer and allows push rod it to descend so that when the carriage reaches the top of its stroke the upper end of push rod It will not engage cam and cause the succeeding descent of the carriage. r'hus, on turning oi the machine by handle lil the carriage will rise to the top of its stroke and remain there until handle lil is returned to the dotted line position shown in Fig. 4. With the machine shut off the movable jaw 2l can be caused to disengage the bottom of the pattern by manipulation of the three-Way valve 32 and on releasing the crosshead 33 from engagement with the top of the flask, the flask can be removed.

In the construction illustrated the flask is a one-piece flask which has the pattern supported therein and the mold material rammed up about it. In making up a mold of this character we prefer to employ a pattern that is diecast of tin or equivalent metal having a relatively lowmelting point. When the mold is completed it may then be baked and When the mold is cured it can be heated to a suiiciently high temperature to melt out the pattern after which the mold is ready to have the casting metal poured therein. The extension 23 and the extensions 2| may form gates or risers for the mold cavity if the contents of the flask is removed therefrom either prior to or after baking.

It will be appreciated from the foregoing description that the present apparatus does not depend upon the mere application oi pressure alone to the molding material in the ask. If pressure alone is relied upon the molding material tends..

to stratify and to have striations developed or formed therein. 4having a combined pressure and a sharp percussive rapping take pla-ce, a uniform ramming up of the mold is possible despite the fact that the lower end of the ramming hammer does not fit the entire flask closely nor docs it t closely about the pattern. By means of this method and apparatus We have been able to ram up molds rapidly, eiiiciently, and secure a high degree of uniformity enabling the casting oi' high melting point alloys and developing highly uniform precision castings.

Various changes may be made in the details of construction without departing vfrom the spirit or scope of the invention as defined by the appended claims.

We claim:

l. A molding machine comprising ilask supporting means, impact means for imparting a series of sharp blows to molding material intro-- duced into a iiask positioned on the flask supporting means, and pressure operated means for forcing the impact means into the askY with uniform pressure regardless of the extent to which it may be introduced into the flask and withdrawing it therefrom, and means for varying the length of time that the impact means is allowed to apply pressure and impacts to the molding material in the flask.

2. A molding machine comprising ask supporting means, a pneumatic hammer adapted to be moved into and to be withdrawn from a ask positioned on the flask supporting means, iluid pressure operated means for moving the pneumatic hammer into and out of the flask, and means for varying the length of time that the pneumatic hammer remains in the ask before being Withdrawn therefrom.

3. A. molding machine comprising flask supporting means adapted to have a flask supported thereon, a pneumatically operated hammer,

f" means movably supporting the pneumatically operated hammer for movement into and out of the ask, a fluid pressure operated piston for reciprocating said means, and a time control means for Varying the length of time that the hammer remains in the flask. 1

sHELLEY M. sTooDY. RALPH L. ABos. 

